China released the first-quarter trade data just days after President Trump urged its leader, Xi Jinping, to clamp down on trade with North Korea. The two leaders met at Mr. Trump’s Mar-a-Lago resort in Florida last week.

With signs indicating that North Korea could be planning a nuclear or missile test as early as Saturday, a United States Navy strike group led by the aircraft carrier Carl Vinson is steaming toward the Korean Peninsula in a show of force. But the Trump administration has indicated that economic pressure — particularly imposed by China, with which North Korea conducts almost 90 percent of its trade — is its preferred form of deterrence.

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The data released on Thursday showed that China’s trade with North Korea grew 37.4 percent in the first quarter of this year from the period in 2016. Chinese exports surged 54.5 percent, and imports increased 18.4 percent, the General Administration of Customs said at a news conference in Beijing.

China buys iron ore, zinc and other minerals from North Korea, as well as growing amounts of seafood and garments manufactured in the North’s well-equipped textile factories. China reported that its imports of North Korean iron were up 270 percent in January and February compared with the period in 2016.

But imports of coal dropped 51.6 percent in the first three months of 2017 compared with the first quarter of last year, said Huang Songping, a spokesman for the customs agency. Coal has been the biggest hard-currency earner among North Korea’s fairly limited menu of exports.

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After the United Nations sanctions were announced, some economists said it was still possible for Chinese businesses to import coal on an off-the-books basis, using transactions that would not be recorded by customs officials.

But since mid-February, Chinese coal traders have said that their business has virtually vanished. “It’s over,” said a coal trader who operates from Dandong, a city on China’s northeastern border that functions as the main center of business with North Korea. The trader spoke on the condition of anonymity because he feared reprisals from the city authorities.